Kinetics of PAH degradation by a new acid-metal-tolerant Trabulsiella isolated from the MGP site soil and identification of its potential to fix nitrogen and solubilize phosphorous

Abstract

Development of an efficient bioinoculum is considered as an appropriate remedial approach to treat the PAHs-metal mixed contaminated sites. Therefore, we aimed to isolate a degrader able to exert an outstanding PAH catabolic potential with added traits of pH-metal-resistance, N-fix or P-solubilization from a manufactured gas plant site soil. The identified strain (MTS-6) was a first low and high molecular weight (LMW and HMW) PAHs degrading Trabulsiella sp. tolerant to pH 5. MTS-6 completely degraded the model 3 [150mgL−1 phenanthrene (Phe)], 4 [150mgL−1 pyrene (Pyr)] and 5 [50mgL−1 benzo[a]pyrene (BaP)] ring PAHs in 6, 25 and 90 days, respectively. Presence of co-substrate (100mgL−1 Phe) increased the biodegradation rate constant (k) and decreased the half-life time (t1/2) of HMW PAHs (100mgL−1 Pyr or 50mgL−1 BaP). The strain fixed 47μgmL−1N and solubilized 58μgmL−1P during PAH metabolism and exhibited an EC50 value of 3–4mgL−1 for Cu, Cd, Pb and Zn. Over 6mgL−1 metal levels was lethal for the microbe. The identified bacterium (MTS-6) with exceptional multi-functional traits opens the way for its exploitation in the bioremediation of manufactured gas plant sites in a sustainable way by employing bioaugmentation strategy.